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이운식,임원일,구평회,주철민 대한산업공학회 2008 산업공학 Vol.21 No.3
This paper considers a transporter scheduling problem under dynamic block transportation environment in shipbuilding. In dynamic situations, there exist the addition or cancellation of block transportation requirements, sudden breakdowns and maintenance of transporters. The transportation of the blocks in the shipyard has some distinct characteristics. Some blocks are available to be picked up at a specific time during the planning horizon while some other blocks need to be delivered before a specific time. These requirements cause two penalty times : 1) delay times incurred when a block is picked up after a required start time, and 2) tardy times incurred when a block shipment is completed after the required delivery time. The blocks are located at different areas in the shipyard and transported by transporters. The objective of this paper is to propose heuristic algorithms which minimize the weighted sum of empty transporter travel times, delay times, and tardy times. Four heuristic algorithms for transporter scheduling are proposed and their performance is evaluated.
다수의 유한 재생산률과 다종의 컨테이너를 고려한동적 폐기물 회수계획 및 다종제품 재생산계획 문제
이운식 한국경영과학회 2019 한국경영과학회지 Vol.44 No.1
This paper considers a dynamic remanufacturing planning problem, in which wastes are collected by multiple container types and can be remanufactured at each period by any value in the set where the rate is the increment of a remanufacturing capacity and is a nonnegative integer. Each container type has a type-dependent carrying capacity and the freight cost is proportional to the number of containers types used. The multiple products are remanufactured by each taking a fixed portion () of the input wastes to satisfy dynamic demands of each product over a discrete and finite time horizon. Also, a start-up cost is only incurred at the first period of a remanufacturing block which is consecutively remanufactured. It is assumed that the related cost (collection and inventory holding costs of the wastes, and the remanufacturing and inventory holding costs of the remanufactured products) functions are concave and backlogging is not allowed. The objective of this paper is to simultaneously determine the optimal waste collection and remanufacturing plans that minimize the total cost to satisfy dynamic demands of the multiple products. In this paper, the optimal solution properties are characterized and then, based on these properties, a dynamic programming algorithm is presented to find the optimal plan. Also, an acyclic network model is proposed to efficiently find the optimal solution to ()-subproblems. Finally a numerical example is introduced to illustrate the procedure for applying the proposed algorithm.
이운식,윤상흠 한국경영공학회 2009 한국경영공학회지 Vol.14 No.1
This paper considers a remanufacturing problem, in which used products(or wastes) are purchased and the used products are remanufactured to satisfy dynamic demands of remanufactured products over a discrete and finite time horizon. Also, as used products are purchased more than or equal to a special quantity Q, a discount price policy is applied. The problem assumes that the related cost (purchasing and inventory holding costs of used products, and the remanufacturing and inventory holding costs of remanufactured products) functions are concave and backlogging is not allowed. The objective of this paper is to simultaneously determine the optimal purchasing for used products and the optimal remanufacturing policies that minimize the total cost to satisfy dynamic demands of remanufactured products. This paper characterizes the properties of the optimal policy and then, based on these properties, presents a dynamic programming algorithm to find the optimal policy. Also, a network model is proposed to efficiently find the optimal solution to (u,v)-subproblems. A numerical example is then introduced to demonstrate the procedure of the proposed algorithm.
단일설비 다종제품의 생산계획문제를 위한 수정된 Part-Period Balancing 알고리즘
이운식,고명한,구평회 한국생산관리학회 2002 한국생산관리학회지 Vol.12 No.3
본 논문은 단일설비로 다종제품을 생산하는 생산시스템에서의 생산계획문제를 다룬다. 이 문제에서 생산기간마다 생산설비는 다종제품을 동시에 생산하고 이때 각 제품의 생산량은 전체 투입자원량의 일정비율(ai>0)로 생산된다. 유한계획기간에서 다종제품의 수요는 동적으로 발생하며 추후조달은 허용되지 않는다고 가정한다. 또한, 관련 비용함수는오목함수라고 가정한다. 본 논문에서는 단일설비 다종제품의 생산계획문제에서 생산계획을 효율적으로 찾을 수 있는 수정된 Part-Period Balancing 알고리즘을 제안한다. 수치예제를 통해 제안된 알고리즘의 적용절차를 ㅓㄹ명하고 다양한 문제들을 대상으로 제안된 알고리즘의 효율성을 검증한다.
납품시간창을 고려한 동적 주문계획, 운송계획 및 아웃바운드 디스패칭 문제
이운식 한국경영공학회 2010 한국경영공학회지 Vol.15 No.3
This paper considers a single-product problem for inbound ordering and shipping, and outbound dispatching at a third-party warehouse, where the demand is dynamic over the discrete time horizon. Each demand must be delivered into the corresponding delivery time window which is the time interval characterized by the earliest and latest delivery dates of the demand. Ordered products are shipped by a container and the freight cost is proportional to the number of containers used. Also, it is assumed that related cost functions are concave and backlogging is not allowed. The paper determines simultaneously the optimal ordering, shipping, and dispatching plans to minimize total costs which include ordering, shipping, and inventory holding costs. The paper characterizes the optimal solution properties and presents a dynamic programming algorithm for finding the optimal solution
프로젝트형 수주생산환경에서의 애로사슬(Critical Chain) 기법의 적용사례
이운식,김민수,김병남,김영미 한국경영공학회 2005 한국경영공학회지 Vol.10 No.1
Lots of research efforts have been exerted to find an efficient way to reduce lead time, and thus gain keen competence in a fierce market environment. Among those efforts, TOC (Theory of Constraints) has widely been recognized as one of the most efficient and cost-effective methods. Generally, TOC consists of DBR(Drum-Buffer-Rope) scheduling and CCPM(Critical Chain Project Management). The former is devised to obtain a production schedule in a typical manufacturing environment; the latter has focused on the project-based make-to-order environments such as shipbuilding, software development, and construction where highly diversified customer needs exist. In contrast to the wide application of DBR scheduling, few studies have been conducted for the implementation of CCPM. In this paper, CCPM scheduling has been applied to a transformer manufacturing process of 'K' company which is a typical project-based make-to-order manufacturing process. A series of experiments has revealed that the CCPM schedule significantly outperforms the conventional scheduling method of that company.